Propolis is materials of beehive, and has been used as folk medicine for anti-topical infection. Despite its known antioxidant capacity, propolis exhibits capacity to induce oxidative DNA damage. This induction of oxidative DNA damage is transient and reaching plateau within 1-3h after treatment. The purpose of this thesis is to disclose the underlying mechanism. Based on previous studies, the induction is hypothesized to be associated with reactive oxygen species generated through the phenolic compounds of propolis. By using comet assay incubate with endoIII/fpg which recognizes oxidative DNA damage site, the induction of DNA lesions was known to require serum. The induction was suppressed by antioxidant such as β-carotene and glutathione (GSH). Representative polyphenolic compound of propolis such as pinocembrin, galangin and chrysin were found to induce oxidative DNA damage. Furthermore, the induction was abolished with deferoxamine, an iron chelator, and the induction could be restored in serum-free medium if iron was supplement. On the other hand, catalase, an enzyme to hydrolyze hydrogen peroxide (H2O2), was effective to suppress the induction and the formation of H2O2 was known by Raman spectral analysis and fox assay in the cell free system containing propolis or pinocembrin and iron ions. Thus, the results suggest that H2O2 is generated through the redox reaction within polyphenolic compounds, metal ions and oxygen, oxidative DNA damage may be caused by H2O2 through Fenton reaction.

蜂膠是一種經由蜜蜂從植物萃取原料所製成的混合物，並且在民俗療法中也認為可用來抵抗局部性細菌感染。儘管蜂膠具有抗氧化的能力已廣為人知，我門研究中卻發現蜂膠顯示出可以誘導氧化性DNA損傷。然而在細胞處理蜂膠之後，所產生的氧化性DNA損傷會在3小時將近修復完畢。這篇論文的目的是在釐清蜂膠是如何促使細胞產生氧化性DNA損傷。根據最近的研究，這個誘導被認定是經由蜂膠裡多酚類化合物產生的氧化性物質所造成的。藉由彗星試驗搭配上可辨認氧化性DNA損傷的 endoIII 及 fpg 酵素，蜂膠所造成的傷害被認為需要血清的參予。並且這些誘導是可以被 β-carotene 及 Glutathione 所抑制。在蜂膠裡代表性的多酚化合物像是pinocembrin，galangin，crysin都會誘導氧化性DNA損傷。然而，這種誘導可以被鐵螯合劑 deferoxamine所抑制，且在無血清的培養基添加鐵並處理蜂膠是可以促使氧化性傷害再次發生。另一方面，藉由可以水解過氧化氫的catalase可以有效的抑制在蜂膠處理過後過氧化氫的產生，並且拉曼光譜分析也確認在不具有細胞的無血清培養基添加了蜂膠及鐵離子在裡面，會有過氧化氫的產生。因此，實驗結果證實多酚化合物會與金屬離子和氧氣藉由氧化還原反應產生過氧化物，也就是說氧化性DNA損傷可能是因為藉由Fenton reaction產生的過氧化物所造成。

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